The ammonia required for the SCR reaction is made available in a tank of the tank device in the form of, in particular, a 32.5% aqueous urea solution, which is also marketed as AdBlue®. The aqueous urea solution is metered into an SCR catalytic converter in the exhaust tract, for example is injected by means of a dosing pump and/or an injector. The components required for the delivery of urea solution are preferably arranged at least partially in an interior and/or on a base of the tank. A disadvantage of the known tank devices is that, during the freezing of the aqueous urea solution owing to very low outside temperatures, a very high pressure may be exerted on the dosing pump, causing mechanical damage to the dosing pump, as a result of an expansion of the aqueous urea solution as it freezes.